tracing: Add a per-event-trigger 'paused' field

Add a simple per-trigger 'paused' flag, allowing individual triggers
to pause.  We could leave it to individual triggers that need this
functionality to do it themselves, but we also want to allow other
events to control pausing, so add it to the trigger data.

Link: http://lkml.kernel.org/r/fed37e4879684d7dcc57fe00ce0cbf170032b06d.1449767187.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 0a62887..e4d8b37 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -72,6 +72,8 @@
 		return tt;
 
 	list_for_each_entry_rcu(data, &file->triggers, list) {
+		if (data->paused)
+			continue;
 		if (!rec) {
 			data->ops->func(data, rec);
 			continue;
@@ -110,6 +112,8 @@
 	struct event_trigger_data *data;
 
 	list_for_each_entry_rcu(data, &file->triggers, list) {
+		if (data->paused)
+			continue;
 		if (data->cmd_ops->trigger_type & tt)
 			data->ops->func(data, rec);
 	}